Commutator.



M. E. THOMPSON.

COMMUTATOR.

APPLICATION FlLED. JUNE 26,1914.

Patented May16, 1916.

AAW i w WIT/VESSES MQW, /Qw

MILTON E. THOMPSON, OF RIDGEWAY, PENNSYLVANIA.

COMMUTATOR.

Specification of Letters Patent.

Patented May 16, 1916.

Application tiled June 26, 1914. Serial No. 847,376.

To all whom t may concern:

Be it known that I, MILTON E. THOMPSON, a citizen of the United States,and a resident of Ridgeway, Elk county, State of Pennsylvania, haveinvented new andl useful Improvements in Commutators, of which thefollowing is a specification.

My invention rela-tes to improvements in commutators and moreparticularly to those of the cylindricaltype comprising conductingsegments with insulating means therebetween. In assembling suchcommutators it is customary to provide dovetail or equivalent faces onthe edges of the segments, then assemble vthe segments with theinsulating means and hold them in assembled position by suitableclamping means. While so held various faces,- which are to be engagedwith means for holding the segments together` in the finishedcommutator, are turned down or bored out in a well-known manner in orderthat these engaging faces will be symmetrical on all the segments. Insuch boring out it often happens that the metal of which the conductingsegments are made will bur over from one segment toits adjacent segment,either causing a short circuit between the adjacent segments ormaterially cutting down the insulation there-between.

The main object of this invention is to provide an arrangement wherebythese disadvantages are overcome and to this end I make the distancebetween the segments much thicker adjacent said bored surfaces than theinsulation separa-ting the segments at their wearing portions so that atthese points the distance across the insulation from one segment to itsadjacent segment will be so great that any burring of the metal will notappreciably affect the insulation between the two segments. In practiceI have made theseparation three times as much at the bored surfaces asat the wearing surfaces, although a somewhat lesser sepa.- ration ispracticable.

A further object of my invention is to provide insulation between suchcommutator segments which may beconveniently and easily assembled and isnot likely to get out of order.

Further objects, features and advantages will more clearly appear fromthe detailed description given below taken in connection with theaccompanying sheet of drawings which forms a part of this specification.

In the drawings, Figure 1 is a transverse section of a portion of acommutator embodying my improvements in one form; and Fig. 2 is an endview of some of the conducting segments with intervening insulation ofthe commutator of Fig. 1.

Referring to the drawings 1-1 represent conducting segments arranged inthe form of a cylinder with insulating means therebetween. Theinsulating means consists of a sheet or strip of mica material 2 betweenadjacent segments and separate sheets of insulating fiber 3 3 one oneach side of the mica sheet 2 and extending only part way from thebottom of the segments to the tops thereof. All of the segments andinsulating strips are provided with bored out or turned down faces 4, 5and 6 forming a sort of dovetail for engagement with members 7 and 7which hold the segments and insulation in place. The members 7 and 7 areprovided with surfaces 8, 9 and 10 which oppose the surfaces 4, 5 and 6and when the bolt 11 is tightened the members 7 and 7 are drawn togethercausing the surfaces 8, 9, and 10 to approach the surfaces 4, 5 and 6and clamp the segments and insulation firmly in position. A sheet ofinsulating fiber 12 and of mica material 13 are interposed between thesurfaces 8 and 4 and rings of mica material 14 are interposed betweenthe surfaces 9 and 5 and 10 and 6 so that the segments 1 are thoroughlyinsulated from the clamping members 7 and 7.

In assembling the commutator the segments 1 and insulating sheets 2, 3are placed in position and held in such position without the members 7and 7 in any suitable manner. Vhile so held the surfaces 4, 5 and 6 arebored out or turned down so that all of such surfaces will besymmetrical and will properly engage the surfaces 8, 9 and 10 whenclamped by the members 7 and 7.

Vhile the sheets of fiber 3, 3 have a different radial length from thesheets 2, and they only extend from the inner ends of the segmentspart-way toward the outer ends or periphery of the segments,nevertheless,- they extend beyond all the bored surfaces such as 4, 5and 6 so that the insulation between two adjacent segments is materiallythicker ad` jacent all bored portions of the segments than adjacent theouter portions of the segments. The segments 1 aie provided withshoulders 15 to accommodate the outer edges of the sheets 3, theseshoulders being outside of the bored surfaces 6, etc. The segments 1 areprovided with slots 16 for the connection of ele trical conductorsthereto and on one side o the commutator the mica sheets 2 are allowedto project beyond the segments outside of the insulating ring 10 tobetter insulate the terminals of these conductors from one another.

As it is difficult to provide an inte al piece of mica insulation ofvarying thickness which will withstand the usage required, and in orderto cheapen the construction without detriment thereto, the insulationbetween two adjacent segments l consists of a plurality of sheets ofinsulating material 2, 3 each of uniform thickness, the middle sheet 2extending out between the segments to the periphery of thel commutatorso that both inner and outer portions of the insulation are of uniformthickness, although, of course, the different sheets 2, 3 may be ofdifferent thickness from one another and if desired one ofthe sheets 3may be omitted between each two segments. By having the outer ortions ofthe insulation of uniform thic ess the commutator may be worn down tothe shoulders 15 by ordinary use without the space between the segmentsunder the brushes increasing, and by having the insulation thicker belowthe shoulders 15 or adjacent the board surfaces 4, 5 and 6 there is nodanger of short circuiting due to burring over o f the metal in theboring operation.

As will be seen from the drawing the insulation acts as means formaintaining the segments a substantially greater distance apart adjacentthe bored surfaces than at the portions provided for wear, and eachcommutator section has its portions provided for wear of substantiallythe same thickness and its lower portions of substantially greateruniform thickness.

Although I have described my improvements in great detail and withrespect to one particular embodiment thereof, I do not desire to belimited to such details except as clearly pointed out in the appendedclaims since many changes and modifications may well be made withoutdeparting from the spirit and scope of my invention in its broader asects.

Having ully and clearly described my invention what I claim and desireto secure by Letters Patent, is

1. A commutator including a number of separated segments each integralthroughout, which, when assembled, have a brush bearing surface and amachined surface, and insulation between the segments, said insulationbeing of a given uniform thickness from the bearing surface through thepoi'- tion of the commutator devoted to wear and of a substantiallygreater thickness at and adjacent to said machined surface whereby thebored parts of adjacent segments are separated by too great a distanceto enable a bur caused by turning down to substantially bridge the spacebetween segments.

2. A cylindrical commutator including a number of separated segmentseach integral throughout, which, when assembled, have a brush bearingsurface on the outer cylindrical surface and an inner cylindrical boredsurface, and insulation between the segments, said insulation being of agiven uniform thickness from said brush bearing surface through theportion of the commutator devoted to wear and of a substantially greaterthickness at and adjacent to said inner bored surface whereby the boredparts of adjacent segments are separated by too great a distance toenable a bur caused by turning down to substantially bridge the spacebetween segments.

3. A commutator comprising conducting segments with insulating meanstherebetween, the segments having bored surfaces for engagement withmeans to hold the segments together, the insulating means between twoadjacent segments being materially thicker adjacent said bored surfacesthan adjacent the outer portions of the segments, and consisting of aplurality of sheets of insulating material each of which is of uniformthickness throughout.

4. A commutator comprising separated conducting segments having abrush-bearing surface, an insulating sheet between each adjacent pair ofsegments extending from the brush-bearing surface to the surfaceopposite the brush-bearing surface and filling the space between thesegments at and adjacent to their outer brush-bearing surface, andadditional insulation between the se ments at and adjacent to thesurface opposite the brush-bearing surface.

5. A conimutator comprising conducting segments each integral throughoutwith insulating means therebetween, the segments having bored surfacesfor engagement with means to hold the segments together, the insulatingmeans between two adjacent se ments being materially thicker adjacentsaid bored surfaces than adjacent the outer portions of the segmentswhereby said insulating means are too thick to allow a bur tosubstantially bridge adjacent segments, and the outer portion of theinsulation being of uniform thickness.

6. A coinmutator comprising conducting segmentseach integral throughoutwith insulating means therebetween, the segments having bored surfacesfor engagement with means to hold the segments together, the insulatingmeans between two adjacent segments being materially thicker adjacentsaid bored surfaces than adjacent the outer' portions of the segmentswhereby said insulating means are too thick to allow a bur tosubstantially bridge adjacent segments, and both inner and outerportions of the insulation being of uniform thickness.

7. A commutator comprising conducting segments with insulating meanstherebetween, the segments having bored surfaces for engagement withmeans to hold the segments together, the insulating means between twoadjacent segments being materially thicker adjacent said bored surfacesthan adjacent the outer portions of the segments and consisting of aplurality of sheets of insulating material each of uniform thickness.

8. A commutator comprising conducting segments with insulating meanstherebetween, the segments having bored surfaces for engagement withmeans to hold the segments together, the insulating means between twoadjacent segments being materially thicker adjacent said bored surfacesthan adjacent the outer portions of the segments and consisting of aplurality of sheets of insulating material, one of said sheets extendingout between the segments to the periphery of the commutator.

9. A commutator comprising conducting segments with insulating meanstherebetween, the segments having bored surfaces for engagement withmeans to hold the segments together, the insulating means between twoadjacent segments being materially thicker adjacent said bored surfacesthan adjacent the outer portion of the segments and consisting of aplurality of sheets of insulating material comprising two sheets ofinsulating fiber with a sheet of mica material therebetween, the micasheet extending out between the segments to the periphery of thecommutator and all of said sheets being of uniform thickness.

l0. A commutator comprising conducting segments with insulating meanstherebetween, the segments having bored surfaces for engagement withmeans to hold the segments together, the insulating means between twoadjacent segments being materially thicker adjacent said bored surfacesthan adjacent the outer portions -of the segments and consisting of aplurality of sheets of insulating material comprising two sheets each ofuniform thickness and a third sheet of uniform thickness extending outbetween the segments to the periphery of the commutator.

1l. A cylindrical commutator comprising conducting segments assembled toproduce a cylindrical brush-bearing surface, insulating members of eventhickness between saidv segments and further insulating pieces betweenthe first-named insulating pieces and the segments and extending onlypart-way from the bottoms of the segments toward the brushbearingsurface of the segments.

12. A cylindrical commutator comprising conducting segments withinsulating means therebetween, the distance across the outer peripheryof which is greater than the distance across the inner peripherythereof, the insulating means between two adjacent segmentsconsisting ofinsulating members of even thickness between the conducting segments andfurther insulating pieces between the first-named insulating pieces andthe conducting segments at the inner ends thereof.

13. A cylindrical commutator comprising conducting segments withinsulating means between the segments, the insulating means between twoadjacent segments consisting' of a plurality of sheets of insulatingmaterial of different lengths in a direction at right angles to thebearing surface of the commutator.

14. A cylindrical commutator comprising conducting segments withinsulating means between the segments, *the insulating means between twoadjacent segments consisting of a plurality of sheets of insulatingmaterial of diiferent lengths in a direction at right angles to thebearing surface of the commutator, said sheets being of uniformthickness.

l5. A cylindrical commutator comprising conducting segments eachintegral throughout with insulating means therebetween of uniformthickness throughout that portion of the commutator provided for wear,the segments having bored surfaces for engagement with means to hold thesegments together, the distance between two adjacent segments beingmaterially greater adjacent said bored surfaces than adjacent the outerportions of the segments, whereby when boring said surfaces the segmentswill not bur over from one to another to cause short circuiting of thesegments.

16. In a cylindrical commutator composed of bored segments each integralthroughout having insulation of uniform thickness clamped between themat the portions provided for wear and means for maintaining the opposedsurfaces of adjacent segments at a substantially greater distance apartthan the thickness of said insulation, where adj acent the boredsurfaces whereby adjacent bored surfaces are sufficiently separated toprevent a bur from substantially bridging the space between segments.

17. A commutatorv including segments each integral throughout havinginsulation between each pair of segments which insula- In testimonywhereof, I have signed my tion is of substantially uniform thickness atname to this specification, in the presence of 1o the portions providedor wear all?1 is of subtwo subscribing witnesses. stantially greater uniorm thic ess at its 5 lower portions whereb at said lower parts MILTONE' THOMPSON' the segments are su ciently separated to Witnesses: preventa bur caused by turning down to EDWIN SEGER, substantially bridge theinsulation. RICHARD Em

